The washing machine is new and I use Rin detergent for the use and I don't know how do I get rid of these if it's happening only on using washing machine then?
If it happens only with white clothes try some color trap along side with the detergent. Also maybe you are using too much of a fabric softener. Try reducing that and see what happens
I use just a RIN detergent with it along with other dark coloured clothes . Should I clean the bright colored ones separate only? And how do I get rid off these stains now?
The stains could be from colors from other clothing. It is not advisable to wash strong color clothing with light ones because there is strong possibilities of having stains. Then secondly check the type of detergent you used because some detergent do not support colors in clothing.
The blotchy marks that are sometimes left on your clothes after you've washed them can be caused by 'scrud', which is a waxy build-up of fabric softener or detergent in the drum of your washing machine